Oxy-fuel welding is a type of thermal cutting that burns fuel and air together to create an open flame. Types of Oxy-Fuel Welding can be done in two ways: shielded metal arc and gas metal arc. This article will discuss Types of Oxy-Fuel Welding, Types Of Oxy-Fuel Welding Equipment, Types Of Oxy-Fuel Welding Techniques, Types Of Flame In Oxy Acetylene Welding, and how do you weld oxy-fuel?
Let's dig into it...
# Table of Contents
What is oxy welding?
Oxy fuel welding is a type of welding that uses only an oxygen-acetylene torch. Welders use the flame to heat metal until it is molten, then they press two pieces together and cool them quickly so that they are permanently joined.
The gas torches used in oxy-fuel welding do not require electricity or any other power source (though propane tanks must be refilled). The welder controls the amount of air to feed into the flame by controlling their hand position on the valve handle.
A regulator attached to each tank provides either constant pressure or variable pressure depending on what you want your weld for. You can also adjust how long you hold down the trigger as well as how much fuel goes through with every pulse based on whether you're using your left hand or right hand.
It involves using a flame that is produced at the welding torch tip in a process that involves use of a filler rod and a metal base. There are up to five different types of oxy fuel welding.
Oxygen and fuel gas do combine in right proportions inside the mixing chamber of the torch. The metal that is melted from the plate edges together with the filler metal when used do intermix in a molten pool and join during cooling. Some of the most popular fuel gases that are used include natural gas, propane, propylene and acetylene.
Types of Oxy Fuel Gas Welding
Oxy-fuel gas welding is a process using oxygen and acetylene gases as the primary energy source to weld metals. The oxy-fuel torch uses the heat from the combustion of these gases to melt the metal being joined. It differs from other forms of welding that use an electric arc as its primary heating element, so it can be used in different atmospheres without the risk of sparking or burning out. Oxy-fuel gas welding is generally not used for joining alloys with high melting points such as steels, nickel-based alloys, titanium alloys, or aluminum because this type of fusion requires temperatures much higher than those achievable by oxy-fuel torches.
But there are many types of oxy-fuel gas welding processes that have been developed over time that are suitable for metals with lower melting points such as copper, bronze, and aluminum. Such as:
01. Air acetylene welding-AAW
Air acetylene welding refers to a gas welding process that is achieved from combustion of air and acetylene. The Air acetylene welding system requires use of a single tank and takes oxygen from the atmosphere. Using a single tank makes it cheaper and very easy to carry around and store.
Its hose together with handle are less cumbersome when using. It is perfect for use in tight spaces and its pipe has a smaller diameter. Air acetylene welding is known to have the hottest flame ranging from 5000 0F to 6000 0F which ensures the job is quickly done. It produces flames.
Using the air acetylene system equipment is quite easy and can be carried around. Its cylinders have regulators that help control gas pressure flow.
Hoses that are flexible are in most cases used in connecting the blowpipe or torch and regulators. It comes with safety devices known as flashback arrestors or flame traps which are well fitted between the regulators and the hoses. The flashback arrestors are important since they help in preventing flames from getting to the cylinders.
02. Oxyacetylene welding-OAW
The oxyacetylene welding which can also be referred to as gas welding is a process that mainly relied in combustion of acetylene and oxygen. Hot flame will be produced when these two gases are brought together in the torch in right proportions.
You can use carburizing, neutral and oxidizing flame settings. The oxyacetylene equipment's are easy to use and very portable. It comprises of acetylene gases and oxygen compressed inside the steel cylinders. Its cylinder is usually fitted with flexible hoses and regulators. Flame traps which act as safety devices are usually fixed in between the regulators and the hoses. It uses flashback to help in preventing the generated flame from getting to the cylinders.
03. Oxygen/Propane welding-O/PW
The Oxygen/Propane welding uses a blend of oxygen and propane gas which is made available in a number of throwaway canister brands, Mapp & Turbo gas and Gasex. The Oxygen/Propane is available in refillable and large cylinders. The gas mixture will burn quite hotter that propane and oxygen which is at approximately 3100⁰C which makes it be considered a perfect welding gas since the jobs will get to the operating temperature faster.
However, it is not suitable for fusion welding. Although there are people who use it in welding, according to a couple of tests which have been produced, the welds it produces are a bit brittle. Although a standard Oxy Acetylene can be used in place of the Oxy Propane, it is still far from ideal.
When right equipment is used, the Oxygen/Propane can be a viable alternative to Oxy Acetylene.
04. Oxy hydrogen welding-OHW
The Oxy hydrogen welding is a process of gas welding that uses combustion mixture of oxygen and Hydrogen to produce flame for gas welding. Hydrogen is burned together with oxygen acting as the fuel.
The temperature of welding in Oxy hydrogen welding is still below that in oxyacetylene welding. The flame color will never be affected by the difference in hydrogen and oxygen mixture hence; it is be more difficult for the welder to make adjustments to the torch.
The 3000 °C high temperatures of concentrated flame will make soft soldering to be possible without having to use any type of deoxidizers or without excess welds overheating.
05. Pressure gas welding-PGW
Pressure gas welding refers to gas welding where the welded parts are pressed onto each other when they are heated using a gas flame. This process is almost similar to the resistance butt welding. However, the pressure gas welding never requires any filler material. You can use pressure gas welding to help you join rods, pipes and railroads rails.
In case the oxygen pressure is high, concavity will always show up on the cut surface. High oxygen pressure can also cause cut surface notching. The oxygen stream high velocity will blow the metal and slag the kerf out quickly ensuring the cut which is started is continuous.
When a low pressure is used, the operation will not run at the right speed. Too much dragging will lead to slag formation while a wide kerf will be produced at the cut bottom. The stinger will become long and coherent as pressure is increased.
How do you weld oxy-fuel?
The oxy-fuel welding process uses a combination of oxygen and fuel gases to create an extremely hot flame. A welding torch is used to direct that heat onto the metals you want to be welded.
When a metal heats, it becomes softer so it can be bent or shaped as desired. This process creates molten pools in which these changes take place; this pooling liquid then cools when pulled away from its source of heat, hardening into new material that cannot be penetrated by outside forces without first being heated again.
The oxy-fuel welder uses his knowledge of how long each kind of metal needs at that temperature before they become soft enough for shaping purposes, as well as alloys’ melting points—which differ depending on their contents--in order to achieve successful results with every project.
Type of tool used in the process
The oxy-fuel welding process is a relatively simple one that uses equipment such as:
- Welding torch.
- Shielding gas.
- Filler rod.
- Oxy-fuel welding rig.
The welder typically works in an industrial setting, fabricating metal parts for vehicles and structures. These materials are often heavy duty and high quality so they must be handled with care to avoid injury or damage.
When handling these metals the use of gloves becomes necessary because the heat from the flame can cause burns on bare skin if touched too long or at all.
It's also recommended that protective eyewear be worn by welders who engage in this type of work regularly; without it, there’s a risk of hurting eyes due to flying sparks, and not just the hot metal being welded.
What are the three types of flame in oxy acetylene welding?
Oxy-acetylene flames come in three types: a neutral flame, carburizing, and an oxidizing flame. All of these differ from each other chemically but also structurally and shape-wise.
- Neutral Flame
The Neutral Flame is one of the types of oxy-fuel welding. Neutral flame means that it has no bias in what it heats, so anything is fair game; you can heat up any type of metal to weld them together, such as steel and aluminum.
Moreover, the Neutral Flame does not have a higher temperature than the other flames do although this should be relatively equivalent between all three flames due to how much oxygen they take in.
It’s typically used for more precise work without making contact with the heated area at all or when using filler rods because there’s less risk of warping during the process. A Neutral Flame is also useful if you need some reaction force on your object but don't want to touch its surface, which is often the case for brazing.
This Neutral Flame is not to be confused with a Natural Gas flame because of how they are used in industry, which will also determine their properties when applied to welding equipment; however, this Neutral Flame can still come from natural gas or even acetylene and oxygen if it’s mixed together.
- Carburizing Flame
Carburizing flame is the second of the types of oxy-fuel welding. It is more intense than Neutral Flame and has a higher temperature because it burns fuel with high carbon content, such as acetylene or natural gas.
Carburizing flame was originally developed for hardening steel but found its use in other industries due to how efficient it can be when working on different types of metals.
This flame is often used to soften metal for better welding and can help in some cases with brazing because it penetrates the surface more deeply than Neutral Flame does, which allows you to draw off excess solder from a joint without burning or melting the surrounding area.
It’s also good at repairing copper pipelines, which Neutral Flame isn’t as good for because it will melt the line and cause bigger problems later on.
- Oxidizing Flame
Oxidizing flame is the most common type of flame used in welding. Unlike the Neutral Flame, this one is yellow with a small amount of blue coloring.
The oxidizing flame provides a higher temperature than the Neutral Flame and so can be more useful for some types of welds (especially those involving aluminum). The greater heat also means that oxidation (rust) will occur quicker; which may require the operator to take additional precautions when leaving equipment unattended or storing materials without proper storage containers.
A trade-off though is that because the oxide layer has been created by oxygen being introduced at high temperatures, it's able to resist corrosion better over time - thus there are benefits as well as drawbacks when comparing an Oxidizing Burner against another type of burner.
Techniques of gas welding
In this part, we'll explore the four primary techniques of gas welding. These include:
- Leftward or Forward Welding.
- Rightward or Backward Welding.
- Vertical Welding.
- Linde Welding.
01. Leftward or Forward Welding
This welding technique is best suited for steel and iron of thickness up to 3mm and bevel plates of a maximum of 6 mm. In this welding technique, the torch is held in the right hand and the filler rod in left, starting from the end of the plate. The angle made by torch tip is 60-70° while that by the filler rod 30-40° to work surface.
02. Rightward or Backward Welding
The Rightward or Backward Welding technique is used on thinner steel and cast iron materials. Rightward or backward gas welding has many advantages over right-side-up, such as better penetration, accessibility of the point of contact, less distortion at the weld area due to metal shrinkage caused by heat.
The angle made by torch tip can be anywhere from 40° - 50° while that with filler rod ranges from 30º - 40° to work surface. Right-sided or back-handed gas welding is a more simple process than traditional side drilling techniques which makes it much easier for beginners who are just starting out in this field.
03. Vertical Welding Technique
This welding technique can be done either leftward or rightward and is started from the bottom of your welded joint. It may then go towards the top of it with oscillating movement to torch and filler rod depending on thicknesses involved.
It can also depend on which side you start with. The torch will make an angle of 25 to 90 degrees depending upon how thick your plates are - though typically around 45° for most applications.
The filler rod is then pushed into the weld puddle with a set of quick, short strokes. The rod will be inserted at an angle of 30° from your joint surface depending on the thicknesses involved.
There are two types of vertical welding techniques: Push and Pull which can both use either rightward or leftward movement.
Push welds are characterized by a downward motion, while Pull is the opposite - upward movement towards your joint surface. The filler rod should be inserted into the puddle at an angle of 30° from your joint surface depending on which direction you start with; leftward or rightward respectively. Push welding can also have oscillating movements like the other technique.
These two techniques can be done with either a rightward or leftward torch angle, so it's important to keep in mind that if you're going for Push welding then your angles will depend on which side of the weld joint you start from.
The most common type is Pull Vertical Welding Technique because there are fewer movements and less chance of distortion since this style keeps the filler rod away from where it should not go.
04. Linde Welding Technique
Linde welding technique involves using an acetylene flame to weld the edges of steel pipes with butts that have a gap of 2.5mm or less at 70° angles. The seam is welded by using excess acetylene flame from welding while rotating constantly so that the horizontal position can only be reached without any distortion on either side.
This requires careful attention to how the torch is held because it was found that rightward welding produces better workmanship than leftward does as this technique provides for greater perfection in quality of workmanship.
It is important that any operator puts on protective clothing and tinted colored goggles when they are welding. Since the flame is less intense when compared to the arc, little UV will be emitted.
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How to oxy fuel weld?
Slowly open the Oxy/Acetylene Equipment cylinder valves using cylinder keys. Start the weld from the left hand end moving towards the right hand side with the blowpipe flame preceding the filler rod in the travel direction. The blowpipe moves on the weld seam whereas the rod moves in a forward and circular motion.
Can you oxy acetylene weld aluminum?
The Oxy-acetylene welding can be used for different purposes. It is also one of the main things which can be used in welding of aluminum. The other welding techniques which are effective in welding aluminum include the Tungsten Inert Gas (TIG) welding and the metal insert gas (MIG) welding.
Last Updated on July 13, 2021 by weldinghubs